On Tue,  2 Jan 2018 16:18:03 -0800
Brandon Williams [off-list ref] wrote:

-int packet_read(int fd, char **src_buf, size_t *src_len,
-		char *buffer, unsigned size, int options)
+enum packet_read_status packet_read_with_status(int fd, char **src_buffer, size_t *src_len,
+						char *buffer, unsigned size, int *pktlen,
+						int options)
 {
-	int len, ret;
+	int len;
 	char linelen[4];
 
-	ret = get_packet_data(fd, src_buf, src_len, linelen, 4, options);
-	if (ret < 0)
-		return ret;
+	if (get_packet_data(fd, src_buffer, src_len, linelen, 4, options) < 0)
+		return PACKET_READ_EOF;
+
 	len = packet_length(linelen);
 	if (len < 0)
 		die("protocol error: bad line length character: %.4s", linelen);
-	if (!len) {
+
+	if (len == 0) {

This change (replacing "!len" with "len == 0") is unnecessary, I think.

 		packet_trace("0000", 4, 0);
-		return 0;
+		return PACKET_READ_FLUSH;
+	} else if (len >= 1 && len <= 3) {
+		die("protocol error: bad line length character: %.4s", linelen);
 	}

This seems to be more of a "bad line length" than a "bad line length
character".

Also, some of the checks are redundant. Above, it is probably better to
delete "len >= 1", and optionally write "len < 4" instead of "len <= 3"
(to emphasize that the subtraction of 4 below does not result in a
negative value).

+
 	len -= 4;
-	if (len >= size)
+	if ((len < 0) || ((unsigned)len >= size))
 		die("protocol error: bad line length %d", len);

The "len < 0" check is redundant.

-	ret = get_packet_data(fd, src_buf, src_len, buffer, len, options);
-	if (ret < 0)
-		return ret;
+
+	if (get_packet_data(fd, src_buffer, src_len, buffer, len, options) < 0)
+		return PACKET_READ_EOF;
 
 	if ((options & PACKET_READ_CHOMP_NEWLINE) &&
 	    len && buffer[len-1] == '\n')